This invention relates to a process for the production of sulfur in granular form and, more particularly, relates to a process for the granulation of sulfur in a rotating drum.
Sulfur is recovered in large quantities from sulfur deposits and natural gas, and is usually stored in solid form in impounded areas at plant sites until it can be processed in suitable form for the market. Suitable forms of elemental sulfur may be slab sulfur or particulate sulfur in the form of prills, pellets, granules or flakes.
The prior art discloses a number of processes for the production of particulate sulfur. In one type of process, sulfur may be melted and the molten sulfur dispersed, or dropped in globular form, into a cooling medium such as a gas or liquid, whereby the molten sulfur solidifies in the form of solid globules or prills. Alternatively, molten sulfur may be solidified in a layer which may be flaked or crushed to produce particulate sulfur. Another process for producing a particulate sulfur is by compaction of finely divided solid sulfur in the presence of a binder. Still other processes involve the prilling or pelletization of liquid sulfur in a fluidized or spouted bed. The prior art also discloses the granulation of sulfur together with amounts of added compounds in a pan or a blender.
The above mentioned processes for the production of particulate elemental sulfur have a number of important disadvantages. The two most important disadvantages are the presence of sulfur dust often inherent in the process of production or resulting from the attrition of particulate sulfur products upon handling and the fire and explosion hazards presented by the sulfur dust. Other disadvantages of the prior art processes reside in the necessity of removing adhering liquid from sulfur produced in processes using a liquid as a cooling medium for molten sulfur and, in other processes, removing added compounds or binders which interfere with the end-use of elemental sulfur. Non-uniformity of the size and shape of particulate sulfur is a common occurrence in many processes.
We have found that the disadvantages of the known processes for the manufacture of particulate sulfur can be avoided or greatly alleviated. Thus, we have found that particulate sulfur can be produced in a process wherein the explosion hazard is substantially avoided and the particulate sulfur is substantially pure, resistant to attrition, hard, and uniformly and closely sized.